This Heuristic is a workaround that is likely viable in the event none of the other Heuristics work.

All this heuristic checks for is the presence of a special file called .devdir,
which is intended as an explicit notation that "This directory is a project root".

An example case where you might need such a Heuristic,
is the scenario where you're not working with a Perl CPAN dist,
but are instead working on a project in a different language,
where Perl is simply there for build/test purposes.